RU2509311C1 - Bridge metre of parameters of passive multielement rlc dipoles - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: device comprises a generator of voltage of n extent, a metering bridge, a differential amplifier, a control device, a zero indicator, an n-cascade differentiator, and also an object of measurement. The first branch of the bridge circuit comprises two serially connected dipoles - a single resistor and a multielement dipole with controlled elements, made in accordance with the scheme of a frequency-independent dipole (FIDP), in parallel to which an RLC dipole of the object of measurement is connected. The second branch comprises two serially connected resistors. To determine generalised parameters of conductivity of the measured multielement dipole, the dipole circuit is tuned, being formed by two dipoles - frequency-independent and measured, - to the mode of frequency independence, under which in FIDP voltage there are no pulses of voltage of all extents, apart from the senior one, n. The metre preserves the property of separate balancing and expanded functional capabilities, making it possible to create devices for determination of parameters of different versions of multielement dipole circuits, having substitution schemes of RLC type.

EFFECT: expansion of functional capabilities of a bridge metre with supply by voltage pulses.

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Description

The invention relates to information-measuring equipment, automation and industrial electronics and can be used to control and determine the parameters of the measurement objects, as well as physical quantities by means of parametric sensors.

Known bridge meter parameters of multi-element passive two-terminal according to the patent of the Russian Federation 2365921, G01R 17/00, Bull. No. 24, 2009, containing a series-connected voltage pulse generator that varies according to the law of power functions, which includes switched rectangular, linear, quadratic and cubic pulse shapers, a bridge circuit for determining the parameters of two-terminal devices with heterogeneous reactive elements (RLC) and zero indicator. To expand the functionality, the second branch contains multi-element two-terminal devices both in the shoulder of the relation (with fixed parameters of the elements) and in the shoulder of the comparison (with adjustable parameters). The disadvantages of such a meter are:

1) the presence of losses and distortion of the shape of the pulses supplying the bridge circuit in the switching circuits;

2) the lack of a unified procedure and the complex form of analytical expressions for calculating the measured parameters for various configurations of the equivalent circuit of objects;

3) the inability to measure the parameters of two-terminal with an infinite resistance (break) between the poles at constant current.

Of the known devices, the closest in technical essence and the achieved results to this invention is a bridge meter for the parameters of multi-element passive two-terminal devices according to the patent of the Russian Federation 2144195, G01R 17/10, Bull. No. 1, 2000. To simplify the equipment, the bridge meter contains a single generator of sequences of voltage pulses of cubic form. The inputs of the differential amplifier are included in the measuring diagonal of the bridge, and three differentiators connected in series to the output of the differential amplifier. The outputs of the differentiators, as well as the output of the differential amplifier are connected to the inputs of the zero indicator. The bridge is balanced after the end of transient processes in its circuits, sequentially leading to a zero voltage value at the outputs of the third, second and first differentiators, and then the differential amplifier. The disadvantages of this bridge meter are:

1) a complex circuit of a branch with a multi-element bipolar relationship and a multi-element balancing bipolar, which includes adjustable resistors, capacitors and inductors;

2) the lack of a unified procedure and the complex form of analytical expressions for calculating the measured parameters for various configurations of the equivalent circuit of objects;

3) the inability to measure the parameters of two-terminal with an infinite resistance (break) between the poles at constant current.

The problem to which the invention is directed is to expand the functionality of the bridge circuit, simplify and unify the procedure for calculating the measured parameters of multi-element passive two-terminal devices.

The problem is solved in that in a bridge meter of parameters of passive multi-element RLC bipolar, containing a voltage pulse generator that varies according to the law of the nth degree of time, the output of which is connected to the input of the four-arm bridge circuit, the first branch of which consists of a series-connected reference resistor in the first arm relations and a multi-element bipolar with balancing elements in the first shoulder of comparison, and the second branch - from the reference resistor in the second shoulder of the relationship of a different adjustable resistor in the second comparison arm, the common output of the ratio arm and the comparison arm of the first branch forms the first output of the bridge circuit output, and the common output of the ratio arm and the comparison arm of the second branch forms the second output of the bridge circuit output, the free output of the comparison arm of the second bridge branch is grounded; a differential amplifier, the inputs of which are connected to the output of the bridge circuit, and the output is connected to an n-cascade differentiator, consisting of n series differentiating RC links; a null indicator, the first input of which is connected to the output of the nth differentiating RC link, the second input is with the output of the (n-1) th RC link, etc., the n-th input is with the output of the 1st RC link , (n + 1) -th input - with the output of a differential amplifier; The control device, the synchronization outputs of which are connected to the synchronization inputs of the pulse generator and the zero indicator, introduces a potentially frequency-independent two-terminal circuit into the shoulder of the comparison of the first branch as a multi-element bipolar circuit with balancing elements, which contains two bipolar circuits connected in parallel, one of which is a resistor capacitive (RC type) consists of a series-connected first capacitor and a first resistor, in parallel with which are connected in series the second capacitor and the second resistor, the other bipolar resistor-inductive circuit (RL type) contains a series-connected first resistor and a first inductor, in parallel with which is connected a series circuit consisting of a second resistor and a second inductor; the common terminal of the poles RC and RL of the two-pole circuits and the shoulder resistor of the relationship of the first branch of the bridge is connected to the first terminal for connecting the two-pole RLC circuit of the measurement object, the second terminal for connecting the two-pole RLC circuit is grounded.

The invention is illustrated in the drawing. The bridge meter of the parameters of passive bipolar contains a generator 1 of voltage pulses in the form of a power time function:

, $$u_{\mathrm{and}}\left(t\right)=\frac{U_m{t}^n}{t_{\mathrm{and}}^n}$$

,

where U _m is the amplitude, t _and is the pulse duration, n is an integer exponent. The output of the generator 1 is connected to the power diagonal of the four shoulders of the bridge electrical circuit. The first branch of the bridge circuit consists of two series-connected bipolar terminals, the first of which contains a single resistor 2, and the second contains a multi-element bipolar circuit 3. The second branch of the bridge circuit consists of two series-connected resistors 4 and 5. The two-terminal 2 and 4 are the shoulders of the relationship, and bipolar 3 and 5 - shoulders comparing the bridge circuit. The general output of the two-terminal 2 and 3 serves as the first output of the bridge circuit, and the general output of the two-terminal 4 and 5 - the second output of the bridge. The output of the bridge circuit is connected to the symmetric input of the differential amplifier 6, the output of which is connected to an n-cascade differentiator containing n series-connected differentiating RC links. The drawing shows a diagram of a bridge meter with power pulses of a cubic shape: n = 3. Differentiator cascades are made on capacitor 7 and resistor 8, capacitor 9 and resistor 10, capacitor 11 and resistor 12. The outputs of the differentiating RC links are connected to the 1st, 2nd, and 3rd inputs of the null indicator 13, and the 4th input is zero the indicator is connected to the output of the differential amplifier 6. The synchronization inputs of the pulse generator 1 and the zero indicator 13 are connected to the synchronization outputs of the control device 14.

The comparison arm of the first branch of the bridge circuit contains a multi-element bipolar 3 with adjustable elements. It consists of two bipolar circuits connected in parallel, the first of which, resistive-capacitive, contains in series a first capacitor 15 and a first resistor 16, in parallel with which a second capacitor 17 and a second resistor 18 are connected in series; the second, resistor-inductive, two-pole circuit contains a series-connected first resistor 19 and a first inductor 20, in parallel with which a second resistor 21 and a second inductor 22 are connected in series. The shoulder of the comparison of the first branch of the bridge also includes the RLC bipolar of the measurement object. As an example, the measurement object is represented by a bipolar circuit containing a parallel-connected first resistor 23 and a series-connected circuit of a capacitor 24, a second resistor 25 and an inductor 26. The first terminal for connecting the RLC bipolar of the measurement object is connected to the common pole of the resistor 2, the capacitor 15 and the resistor 19. The second terminal for connecting the measurement object is grounded.

Consider the operation of a bridge meter. When a bridge circuit is excited by a cubic pulse

$$u_{\mathrm{and}}\left(t\right)=\frac{U_m{t}^3}{t_{\mathrm{and}}^3}\left(\text{one}\right)$$

voltage pulses appear on the output of the first branch of the bridge, which contain free and forced components. After the end of transient processes, a signal is established at the output of the first branch of the bridge circuit, which contains voltage pulses of the form of a power time function with exponents from 3 to 0:

$$u_{\mathrm{at}sx\mathrm{.one}}\left(t\right)=\frac{H_0{U}_m{t}^3}{t_{\mathrm{and}}^3}+\frac{3H_{\mathrm{one}}{U}_m{t}^2}{t_{\mathrm{and}}^3}+\frac{6H_2{U}_{m}t}{t_{\mathrm{and}}^3}+\frac{6H_3{U}_m}{t_{\mathrm{and}}^3},\left(\text{2}\right)$$

where H ₀ , H ₁ , H ₂ , H ₃ are the generalized parameters of the transfer function H (p) of the first branch of the bridge chain. This function has the form

$$H\left(p\right)=\frac{\mathrm{one}}{\mathrm{one}+R_2\left(Y_{R\mathrm{uh}}\left(p\right)+Y_{dP}\left(p\right)\right)},\left(\text{3}\right)$$

where Y _re (p) is an operator image of the complex conductivity of a two-terminal 3 with adjustable elements; Y _dp (p) is an operator image of the complex conductivity of the measured bipolar. The output voltage of the second bridge branch, the resistor divider R ₄ -R ₅ , repeats the shape of the supply pulse

$$u_{\mathrm{at}sx.2}\left(t\right)=\frac{R_5}{R_{\mathrm{four}}+R_5}\frac{U_m{t}^3}{t_{\mathrm{and}}^3}.\left(\text{four}\right)$$

As can be seen, the balancing of the signals u _{output 1} and u _{output 2 is} possible provided that in expression (2) there will be no voltage components of all degrees except the highest, i.e. nth:

$$u_{\mathrm{at}sx\mathrm{.one}}\left(t\right)=\frac{H_0{U}_m{t}^3}{t_{\mathrm{and}}^3}.\text{(5)}$$

Therefore, the regulation of the elements of the bipolar 3 should lead to zero the parameters H ₁ , H ₂ , H ₃ , ... the transfer function H (p). We express the H-parameters of the transfer function (3) through the Y-parameters of the two-terminal 3 and two-terminal of the measurement object. Since when the circuits are connected in parallel, their conductivity parameters are summed, we will consider both two-terminal networks as a single two-terminal network with complex conductivity

Y (p) = Y _pe (p) + Y _dp (p).

We use the transformations of the generalized parameters of the two-terminal circuits presented in the article. Ivanova V.I. and Titova B.C. Equivalent transformations of the generalized parameters of two-terminal devices for the identification of complex measuring circuits // Sensors and Systems. - 2012. - No. 5. - S.11-16. Formulas for H-parameters using the Y-parameters of a two-terminal device have the form:

$$\begin{array}{l}{H}_0=\frac{\mathrm{one}}{\mathrm{one}+R_2{Y}_0};H_{\mathrm{one}}=-\frac{R_2{Y}_{\mathrm{one}}}{{\left(\mathrm{one}+R_2{Y}_0\right)}^2};H_2=-\frac{R_2{Y}_2}{{\left(\mathrm{one}+R_2{Y}_0\right)}^2}+\frac{R_2{Y}_{\mathrm{one}}^2}{{\left(\mathrm{one}+R_2{Y}_0\right)}^3};\\ H_3=-\frac{R_2{Y}_3}{{\left(\mathrm{one}+R_2{Y}_0\right)}^2}+\frac{2R_2{Y}_{\mathrm{one}}{Y}_2}{{\left(\mathrm{one}+R_2{Y}_0\right)}^3}-\frac{R_2{Y}_{\mathrm{one}}^3}{{\left(\mathrm{one}+R_2{Y}_0\right)}^{\mathrm{four}}};...\text{(6)}\end{array}$$

From formulas (6) it follows that the equilibrium conditions of the signals u _{output 1} and u _{output 2} require that all Y-parameters of the two-terminal network, except Y ₀ , vanish. This property is possessed by frequency-independent bipolar (PNP). The operator image of the complex conductivity of a passive bipolar circuit has the form of a fractional rational function

$$Y\left(p\right)=\frac{b_0+b_{\mathrm{one}}p+b_2{p}^2+b_3{p}^3+...}{a_0+a_{\mathrm{one}}p+a_2{p}^2+a_3{p}^3+...},\left(\text{7}\right)$$

where the values of a ₀ , a ₁ , a ₂ , ... in the denominator and b ₀ , b ₁ , b ₂ , ... in the numerator are determined by the configuration of the two-terminal circuits and the values of the parameters of the elements. The Y-parameters of a two-terminal network are determined by the recurrence formula (see the article by Ivanov V.I., Titova V.S., Golubova D.A. Application of generalized parameters of a measuring circuit for identification of multi-element two-terminal devices // Sensors and Systems. - 2010. - No. 8. - S. 43-45);

$$Y_0=\frac{b_0}{a_0};Y_{\mathrm{one}}=\frac{b_{\mathrm{one}}-Y_0{a}_{\mathrm{one}}}{a_0};Y_2=\frac{b_2-Y_0{a}_2-Y_{\mathrm{one}}{a}_{\mathrm{one}}}{a_0};Y_3=\frac{b_3-Y_0{a}_3-Y_{\mathrm{one}}{a}_2-Y_2{a}_{\mathrm{one}}}{a_0};...\left(8\right)$$

Remove from the numerator and denominator (7) the free terms a ₀ and b ₀ :

$$Y\left(p\right)=Y_0\cdot \frac{\mathrm{one}+\frac{b_{\mathrm{one}}}{b_0}p\frac{b_2}{b_0}{p}^2+\frac{b_3}{b_0}{p}^3+...}{\mathrm{one}+\frac{a_{\mathrm{one}}}{a_0}p+\frac{a_2}{a_0}{p}^2+\frac{a_3}{a_0}{p}^3+...},\text{(9)}$$

- вещественная величина (в См). Если выполняются условия Where $$Y_0=\frac{b_0}{a_0}$$

- real value (in cm). If the conditions are met

$$\frac{b_{\mathrm{one}}}{b_0}=\frac{a_{\mathrm{one}}}{a_0};\frac{b_2}{b_0}=\frac{a_2}{a_0};\text{A.}\frac{b_3}{b_0}=\frac{a_3}{a_0};...,\left(\text{10}\right)$$

.then the conductivity of the two-terminal network will have a resistive, frequency-independent, character: $$Y\left(p\right)=Y_0=\frac{b_0}{a_0}$$

.

We represent conditions (10) in another form:

$$a_0{b}_{\mathrm{one}}-a_{\mathrm{one}}{b}_0=0;a_0{b}_2-a_2{b}_0=0;a_0{b}_3-a_3{b}_0=0;...\left(\text{eleven}\right)$$

Expressions (11) are included in formulas (8), therefore, for a frequency-independent bipolar, all Y-parameters, except Y ₀ , are equal to zero. In this case, the H-parameters of the first branch of the bridge circuit, except for H ₀ , are also equal to zero.

As a rule, the NPPD circuit contains two bipolar circuits connected in series or in parallel, one of which is resistive-capacitive (RC), and the second is resistive-inductive (RL). With a serial connection of two-terminal networks, their Z-parameters with the same indices are added, and with parallel connection, Y-parameters. If, in the absence of the two-terminal object of the measurement, the two-terminal 3 is set to the state of the NPD, then when the measured two-terminal is connected, the conditions of frequency independence of the entire common two-terminal will be violated. By adjusting the parameters of the two-terminal 3, it is necessary to compensate for the terms of the Y-parameters introduced by the measured two-terminal.

Bipolar 3 contains two parallel circuits: RC bipolar C ₁₅ -R ₁₆ -C ₁₇ -R ₁₈ and RL bipolar R ₁₉ -L ₂₀ -R ₂₁ -L ₂₂ . We define the Y-parameters of the two-terminal 3, having previously determined the Y-parameters RC and RL of the two-terminal.

The operator image of the conductivity of the RC bipolar is

$$Y_{RC}\left(p\right)=\frac{C_{\mathrm{fifteen}}p+\left(R_{16}+R_{\mathrm{eighteen}}\right)C_{\mathrm{fifteen}}{C}_{17}{p}^2}{\mathrm{one}+\left[R_{16}{C}_{\mathrm{fifteen}}+\left(R_{16}+R_{\mathrm{eighteen}}\right)C_{17}\right]p+R_{16}{C}_{\mathrm{fifteen}}{R}_{\mathrm{eighteen}}{C}_{17}{p}^2}.\left(\text{12}\right)$$

Y-parameters of RC bipolar equal

$$Y_0^{\text{'}\text{'}}=0;Y_{\mathrm{one}}^{\text{'}\text{'}}=C_{\mathrm{fifteen}};Y_2^{\text{'}\text{'}}=-R_{16}{C}_{\mathrm{fifteen}}^2;Y_3^{\text{'}\text{'}}=R_{16}^2{C}_{\mathrm{fifteen}}^2\left(C_{\mathrm{fifteen}}+C_{17}\right).\left(\text{13}\right)$$

The operator image of the conductivity RL of a two-terminal network has the form

$$Y_{RL}\left(p\right)=\frac{R_{21}+\left(L_{\mathrm{twenty}}+L_{22}\right)p}{R_{19}{R}_{21}+\left[R_{19}\left(L_{\mathrm{twenty}}+L_{22}\right)+R_{21}{L}_{\mathrm{twenty}}\right]p+L_{\mathrm{twenty}}{L}_{22}{p}^2}.\left(\text{fourteen}\right)$$

The y-parameters of the RL bipolar are equal

$$\begin{array}{l}{Y}_0^{"}=\frac{\mathrm{one}}{R_{19}};Y_{\mathrm{one}}^{"}=-\frac{L_{\mathrm{twenty}}}{R_{19}^2};Y_2^{"}=\frac{L_{\mathrm{twenty}}^2\left(R_{19}+R_{21}\right)}{R_{19}^3{R}_{21}};\\ Y_3^{"}=-\frac{L_{\mathrm{twenty}}^2}{R_{19}^2{R}_{21}^2}\left(\frac{L_{\mathrm{twenty}}{\left(R_{19}+R_{21}\right)}^2}{R_{19}^2}+L_{22}\right).\left(\text{fifteen}\right)\end{array}$$

The Y-parameters of the frequency-independent bipolar 3 with indices 0, 1, 2, 3 are found by summing Y 'and Y ″:

$$\begin{array}{l}{Y}_0=\frac{\mathrm{one}}{R_{19}};Y_{\mathrm{one}}=-\frac{L_{\mathrm{twenty}}}{R_{19}^2};Y_2=\frac{L_{\mathrm{twenty}}^2\left(R_{19}+R_{21}\right)}{R_{19}^3{R}_{21}}-R_{16}{C}_{\mathrm{fifteen}}^2;\\ Y_3=R_{16}^2{C}_{\mathrm{fifteen}}^2\left(C_{\mathrm{fifteen}}+C_{17}\right)-\frac{L_{\mathrm{twenty}}^2}{R_{19}^2{R}_{21}^2}\left(\frac{L_{\mathrm{twenty}}{\left(R_{19}+R_{21}\right)}^2}{R_{19}^2}+L_{22}\right).\left(\text{16}\right)\end{array}$$

Operator image of RCL conductivity of a two-terminal device of measurement R ₂₃ -C ₂₄ -R ₂₅ -L ₂₆

$$Y_{RCL}\left(p\right)=\frac{\mathrm{one}+\left(R_{23}+R_{25}\right)C_{24}p+L_{26}{C}_{24}{p}^2}{R_{23}+R_{23}{R}_{25}{C}_{24}p+R_{23}{L}_{26}{C}_{24}{p}^2}.\left(\text{17}\right)$$

Y-parameters of the measured two-terminal are equal

$$Y_0^{\text{'}\text{'}"}=\frac{\mathrm{one}}{R_{23}};Y_{\mathrm{one}}^{\text{'}\text{'}"}=C_{24};Y_2^{\text{'}\text{'}"}=-R_{25}{C}_{24}^2;Y_3^{\text{'}\text{'}"}=C_{24}^2\left(R_{25}^2{C}_{24}-L_{26}\right).\left(\text{eighteen}\right)$$

The balancing of the voltages u _out.1 (t) and u _out.2 (t) in the measuring diagonal of the bridge at the first stage occurs under the condition:

$$\frac{R_{19}{R}_{23}}{\left(R_{19}+R_{23}\right)R_2}=\frac{R_5}{R_{\mathrm{four}}}.\left(\text{19}\right)$$

At the following stages, for equilibrium, the total generalized conductivity Y ′, Y ″, and Y ′ ″ for each index must be brought to zero:

$$C_{\mathrm{fifteen}}-\frac{L_{\mathrm{twenty}}}{R_{19}^2}+C_{24}=0;\left(\mathrm{twenty}\right)$$

$$\frac{L_{\mathrm{twenty}}^2\left(R_{19}+R_{21}\right)}{R_{19}^3{R}_{21}}-R_{16}{C}_{\mathrm{fifteen}}^2-R_{25}{C}_{24}^2=0.\left(\text{21}\right)$$

$$R_{16}^2{C}_{\mathrm{fifteen}}^2\left(C_{\mathrm{fifteen}}+C_{17}\right)-\frac{L_{\mathrm{twenty}}^2}{R_{19}^2{R}_{21}^2}\left(\frac{L_{\mathrm{twenty}}{\left(R_{19}+R_{21}\right)}^2}{R_{19}^2}+L_{22}\right)+C_{24}^2\left(R_{25}^2{C}_{24}-L_{26}\right)=0.\left(22\right)$$

The balancing process is carried out in the same sequence in which the equilibrium conditions (19) - (22) are given. In order to selectively control the amplitudes of the cubic, quadratic and linear components of the voltage in the measuring diagonal of the bridge, the output voltage of the differential amplifier is supplied to the differentiator, which contains three differentiating RC links in series: capacitor 7 and resistor 8, capacitor 9 and resistor 10, capacitor 11 and resistor 12. The outputs of the stages of the differentiator and differential amplifier are connected to the inputs of the zero indicator (NI) 13. The operation of the NI and the pulse generator 1 is synchronized tsya control unit 14 (CU). At the output of the third stage of the differentiator, after triple differentiation of the output voltage of the differential amplifier, at the end of the transition process, a constant voltage u _3RC is formed and is _transmitted to the first input of the null indicator 13, proportional to the difference in the amplitudes of the cubic components of the output signals of the first and second branches of the bridge circuit.

Compensation of the cubic component is carried out by reducing the output voltage of the third RC link to zero by adjusting the resistance R _{5 of the} resistor 5 with the set value of the resistance R _{19 of the} resistor 19 or by adjusting the resistance R _{19 of the} resistor 19 with a fixed value of the resistance R _{5 of the} resistor 5.

Then analyze the voltage u _2RC supplied to the second input NI from the output of the second RC-link differentiator. As a result of compensation of the cubic component and two-fold differentiation of the output voltage of the differential amplifier at the end of the transition process, the voltage u _2RC will be proportional to the amplitude of the quadratic component of the output voltage of the first branch of the bridge:

, $$u_{2RC}\left(t\right)=\frac{6{\left(RC\right)}^2{H}_{\mathrm{one}}{U}_m{K}_{d.\mathrm{at}}}{t_{\mathrm{and}}^3}$$

,

where K _dy is the transmission coefficient of the differential amplifier 6. Compensation of the quadratic component is carried out by bringing the output voltage of the second RC link to zero by adjusting the capacitance of the capacitor 15 with a fixed inductance of the coil 20, or by adjusting the inductance of the coil 20 with a fixed capacitance of 15. This parameter H _{1 is} reduced to zero: H ₁ = 0.

Next, they analyze the voltage u _1RC established at the end of the transition process at the output of the first differentiating RC link, which, after compensating for the cubic and quadratic components as a result of differentiation, is proportional to the amplitude of the linear component of the output voltage of the first branch of the bridge:

. $$u_{\mathrm{one}RC}\left(t\right)=\frac{6RC\cdot H_2{U}_m{K}_{d.\mathrm{at}}}{t_{\mathrm{and}}^3}$$

.

This voltage is supplied to the third input of NI. Compensation of the linear component of the voltage is carried out by reducing the output voltage of the first RC link to zero by adjusting the resistance of the resistor 16 with a fixed resistance of the resistor 21 or by adjusting the resistance of the resistor 21 with a fixed resistance of the resistor 16. In this case, the parameter Н _{2 is} reduced to zero: Н ₂ = 0.

And finally, to compensate for the DC component of the voltage at the output of the first branch of the bridge, the output voltage of the differential amplifier 6 is brought to zero

, $$u_{d.\mathrm{at}}\left(t\right)=\frac{6H_3{U}_m{K}_{d.\mathrm{at}}}{t_{\mathrm{and}}^3}$$

,

which is fed to the fourth input of the zero indicator, adjusting the capacitance of the capacitor 17 with a fixed inductance of the coil 22, or by adjusting the inductance of the coil 22 with a fixed capacitance of the capacitor 17. In this case, the parameter H _{3 is} reduced to zero: H ₃ = 0.

After four stages of balancing the output voltages of the first and second branches of the bridge, the parameters of the elements of the measured bipolar RLC circuit are calculated using formulas (19) - (22). In particular, for the given example, the resistance R ₂₃ , the capacitance C ₂₄ , the resistance R ₂₅ and the inductance L _{26 are} respectively equal:

$$R_{23}=\frac{R_2{R}_5{R}_{19}}{R_{\mathrm{four}}{R}_{19}-R_2{R}_5};\left(\text{23}\right)$$

$$C_{24}=\frac{L_{\mathrm{twenty}}}{R_{19}^2-C_{\mathrm{fifteen}}};\left(\text{24}\right)$$

$$R_{25}=\frac{\mathrm{one}}{C_{24}^2}\left(\frac{L_{\mathrm{twenty}}^2\left(R_{19}+R_{21}\right)}{R_{19}^3{R}_{21}}-R_{16}{C}_{\mathrm{fifteen}}^2\right);\left(\text{25}\right)$$

$$L_{26}=\frac{R_{16}^2{C}_{\mathrm{fifteen}}^2\left(C_{\mathrm{fifteen}}+C_{17}\right)}{C_{24}^2}-\frac{L_{\mathrm{twenty}}^2}{R_{19}^2{R}_{21}^2{C}_{24}^2}\left(\frac{L_{\mathrm{twenty}}{\left(R_{19}+R_{21}\right)}^2}{R_{19}^2}+L_{22}\right)+R_{25}^2{C}_{24}.\left(\text{26}\right)$$

A bridge meter allows you to determine the parameters of bipolar and with zero conductivity (open circuit) between their poles in direct current. In the above example, this is equivalent to the absence of a resistor 23, i.e. R ₂₃ = ∞. The equilibrium condition of the bridge at the first stage has the form

R ₄ R ₁₉ = R ₂ R ₅ ,

which follows from formula (23). In expressions (24) - (26), the value of R _{23 is} not included, and the remaining stages of balancing are carried out according to the above rules.

Thus, an extension of the meter’s functionality has been obtained, the measurement process has been unified at the stages of determining the generalized parameters of the measured two-terminal network, analytical expressions have been simplified to calculate the desired electrical parameters of the circuit elements: resistor resistors, capacitor capacitors, coil inductances.

Claims (1)

A bridge meter of parameters of passive multi-element RLC two-terminal circuits containing a voltage pulse generator that varies according to the law of the nth degree of time, the output of which is connected to the input of the four-arm bridge circuit, the first branch of which consists of a series-connected reference resistor in the first arm of the ratio and a multi-element two-terminal with balancing elements in the first shoulder of the comparison, and the second branch of the reference resistor in the second shoulder of the relationship and a single adjustable resistor in the second shoulder comparison, the total output ratio shoulder and shoulder comparing the first leg forms a first terminal of the bridge circuit output and the total output ratio shoulder and shoulder comparing the second branch - a second output circuit output bridge free shoulder comparison output of the second branch of the bridge is grounded; a differential amplifier, the inputs of which are connected to the output of the bridge circuit, and the output is connected to an n-cascade differentiator, consisting of n series differentiating RC links; a null indicator, the first input of which is connected to the output of the nth differentiating RC link, the second input is with the output of the (n-1) th RC link, etc., the n-th input is with the output of the 1st RC link , (n + 1) -th input - with the output of a differential amplifier; a control device, the synchronization outputs of which are connected to the synchronization inputs of a pulse generator and a zero indicator, characterized in that as a multi-element bipolar circuit with balancing elements, a potentially frequency-independent bipolar circuit is introduced into the shoulder of the comparison of the first branch, which contains two bipolar circuits connected in parallel, one of which the resistive-capacitive (RC type) consists of a series-connected first capacitor and a first resistor, in parallel with which therefore connected second capacitor and second resistor, the other two-pole circuit-inductive resistor (RL type) comprises a series connection of a first resistor and a first inductor, which is included in parallel a series circuit consisting of a second resistor and a second inductor; the common terminal of the poles RC and RL of the two-pole circuits and the shoulder resistor of the relationship of the first branch of the bridge is connected to the first terminal for connecting the two-pole RLC circuit of the measurement object, the second terminal for connecting the two-pole RLC circuit is grounded.